Attachment device for heavy duty cranes



Oct 25, 1950 E. K. THACKER 2,957,592

ATTACHMENT DEVICE FOR HEAVY DUTY CRANES Filed July 21, 1958 INVENTOR. E rnest K. Thacker Attorneys flie S t s Pw i ATTACHMENT DEVICE FOR HEAVY DUTY CRANES Ernest K. Thacker, 1710 W. Charleston Blvd., Las Vegas, Nev.

Filed July 21, 1958, Ser. No. 749,962

'5 Claims. (Cl. 212-145) This invention relates generally to a mobile load distributing attachment for use with heavy duty vehicles, as

2,957,592 Patented Oct. 25 1960 portable over the highways, in the manner conventional for example, heavy duty cranes, track mounted booms,

and the like.

As is well known, various types of truck mounted cranes or derricks have been developedfor hoisting operations remote from the factory or home base of operation. Useful as they are, these truck mounted cranes are frequently incapable of handling a hoisting operation because of the concentrated weight distribution imposed on the rear wheels of the crane unit. A frequent result is damage to the roadway or other bearing surface, or the crane itself may become mired so as to be unusable. A problem therefore arises when a load to be hoisted is greater than the resistance of the bearing surface upon which the crane must operate.

Heretofore, one solution to this problem has been the use of extensible outrigger beams, supported at their ends by jacks or floats. A difficulty arises with this arrangement however because the floats prevent movement of the crane with the load so that a limited placement of a crane load results. In some instances a proper placement can only be obtained by a series of successive hoists with movement of the floats between each hoisting operation, at considerable waste of time and manpower.

It is a general object of the present invention to provide an attachment for use with vehicles of the above character by which the weight of the vehicle may be distributed uniformly over a substantially increased bearing area, without any loss of mobility of the vehicle.

Another object of the invention is to provide a loaddistributing attachment including auxiliary wheels by which a predetermined portion of the total weight can be uniformly distributed or transferred to such wheels.

Another object is to provide a load-distributing attachment of the above type that will permit operation of the vehicle on uneven terrain, and without loss of traction of the driving wheels of the vehicle.

Additional objects and features of the invention will appear from the following description in which a preferred embodiment of the invention has been set forth in detail, in conjunction with the accompanying drawing.

Referring to the drawing:

Figure 1 is a view in perspective of a heavy duty mobile crane incorporating a weight distributing attachment embodying the invention.

Figure 2 is an enlarged perspective view of the attachment device of Figure 1, showing details of its construction.

Figures 3 and 4 are respectively front and side elevational views of the attachment device.

'Figure 5 is a perspective view, like Figure 2, of a modified form of the attachment device.

Figure 1 illustrates my invention as particularly adapted to a heavy duty crane of the truck mounted type, for example, one having a main frame 10 mounting a boom 12. The main frame is supported for movement on rear carrying wheels 14 which customarily provide to any truck mounted equipment.

Figure 1 also illustrates the structure of the outrigger beams 24. These beams are slidably mounted in the main frame 10 so that they can be extended laterally to either side or retracted. Preferablythe extending ends of the beams are apertured to receive attachment bolts or pins, for a purpose hereinafter to be described.

In providing for improved weight distribution without loss of mobility, I have provided a mobile weight transfer attachment 30 secured to the ends of the extensible outrigger beams (Figure 1). As illustrated in Figures 2 to 4 my new attachment device preferably includes a box-like wheel mount 32 which can be openat the top and at one end to facilitate attachment to a sliding outrigger beam. Each of the mounts 32 is supported on a plurality of auxiliary wheels 38 by means of the stub axles 40 carried by the pivot plates 34. As illustrated, the plates 34 are pivotally secured adjacent their centers to a plurality of flanges 36 extending downward from the box-like mounts 32. Desirably, the mounts 32 are provided with apertures 42, corresponding to'the apertures in the ends of the riding outrigger beams, to permit rigid attachment of the devices 30 to the ends of the beams.

Operation of the mobile crane of the invention may be briefly described as follows: The vehicle is adapted to be moved over the highways to the site of the hoisting operation. The outrigger beams 24 are extended and the rolling outrigger attachments secured to the end of the beams as in Figure l. The boom can now be rotated on the turntable 18 to a position over the load, and the hoist mechanism 22 operated to suspend the load. In this position, the attachment devices 30 serve to distribute the load over a much larger area than normally possible, and also to remove a portion of the load from the rear wheels 14. The entire unit can now be moved over the ground to secure a desired placement of the load. During such movement the ends of the outrigger beams are supported in rolling fashion by the auxiliary wheels 38 of the attachment devices. This rolling support permits easy movement of the crane and its load in response to normal traction of the driving wheels 14, since excessive loads are not imposed. The pivotal mounting of the wheel supporting plates 34 also facilitates operation of the crane on uneven terrain, and insures against accidental loss of driving traction.

From the above description of a preferred embodiment, it will be apparent that the present invention provides a mobile crane capable of providing a rolling distribution of a load over a substantially increased bearing area, and permits far greater loads to be movably transported than has been heretofore possible. The mobile unit of the invention provides this result without danger of cracking or other damage to the bearing surface, or loss of mobility due to the crane unit sinking into such surface or otherwise becoming mired and immobile.

To those skilled in the art to which this invention relates, many changes in construction and widely different embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. For example, although the principal illustrated embodiment of the attachment device employs but four auxiliary wheels, devices employing more or even less wheels can be employed without substantial variance from the principles of the invention. Thus Figure 5 illustrates a device employing eight auxiliary wheels 38a, mounted on elongated pivot plates 34a, as might be used in transporting and placing very heavy loads. Accordingly, it should be understood that the disclosures and description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. In a mobile crane, a structure including a main frame, carrying wheels supporting said main frame, at least two slidably extensible outrigger beams secured to said frame, said beams being laterally extensible in opposite directions, and a mobile weight transfer attachment secured to each of said beams, each of said attachments including a box-like wheel mount, wheel-supporting means pivotally secured on a horizontal axis to said wheel mount, and a plurality of auxiliary wheels supported on said wheel-supporting means.

2. A crane as in claim 1, wherein said wheel-supporting means are mounted on said wheel mounts for pivotal movement about an axis parallel to said extensible beams.

3. A motor-powered crane as in claim 1, wherein said wheel-supporting means of each attachment includes separate stub shafts, each mounting at least two auxiliary wheels for independent pivotal movement adjacent the beam end.

4. In a mobile crane, a structure including a main frame, front and rear carrying wheels supporting said main frame, a pair of parallel laterally extensible outrigger beams secured to said frame, and a pair of mobile weight transfer attachments secured to said beams, each of said attachments including a box-like wheel mount, wheel-supporting means pivotally secured on a horizontal axis to said wheel mount, and a plurality of auxiliary wheels supported on said wheel-supporting means whereby said beams and attachment are capable of providing a desired weight distribution over moderately uneven terrain without loss of mobility to said crane.

5. In a motor-powered crane, a mobile Structure including a main frame, a turntable on said main frame rotatable about a vertical axis, a boom pivoted to the turntable so as to be raised and lowered, hoisting mechanism on the turntable connected with the boom for raising and lowering it and for suspending loads on the boom, carrying wheels supporting said main frame, a pair of parallel laterally extensible outrigger beams secured to said frame, and a mobile weight transfer attachment secured to the outer end of each of said extensible beams, each of said attachments including a beam-receiving wheel mount, wheel-supporting means secured to said wheel mounts for pivotal movement with respect thereto on axes parallel to said extensible beams and a plurality of auxiliary wheels supported on said wheel-supporting means, whereby said crane is adapted to substantially full capacity operation over moderately uneven terrain, without overstressing of said outrigger beams.

References Cited in the file of this patent UNITED STATES PATENTS 

